The invention relates to a transglutaminase gene and a transglutaminase obtained therefrom.
Transglutaminase (hereafter, referred to as TGase) catalyzes intramolecular or intermolecular formation of ε-(γ-Gln)-Lys covalent bond, and the crosslink between protein molecules forms gel protein with a tertiary structure. The gel protein can be applied in the food-processing industry, including meat, fish, soybean, wheat, milk, or egg, as a new protein food or gel membrane.
TGases has been found in various tissues and organs of mammals and plants. The first commercialized TGase was isolated from the liver of guinea pig, however, its price is relatively high, about 80 US dollars per unit, because of the difficulties of acquisition. The high price also restricts its use in the food-processing industry. In addition, the technology of isolating TGases from fish or plants is immature. Large scale production of TGase is, therefore, an important task.
It has been found that many strains of microbes produce TGases. Those whose TGases have been cloned include Streptoverticillium S-8112 (Washizu et al., 1994), Streptoverticillium mobaraense (Pasternack et al., 1998), Streptomyces lydicus (Bech et al., 1996), Bacillus subtilis (Kobayashi et al., 1998). Those having exocrine TGase include S-8112 (Ando et al., 1989), S. mobaraense (Pasternack et al,, 1998), S. cinnamoneum (Duran et al., 1998), and S. lydicus (Bech et al., 1996). According to Wu et al. (1996), most TGases derived from Streptoverticillium sp. are exocrine. In the twenty strains of Streptoverticillium sp. tested by Wu et al., TGase derived from Streptoverticillium ladakanum has highest activity. The expression activity of those genes, however, are still restricted in some way, therefore, obtaining a TGase with high expression activity is still required.